linux-kernel - Re: [PATCH v10 04/10] arm64/sysreg: Add a comment that the sysreg file should be sorted

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Message-ID: <CAL_JsqJFgunOVqpXnj+0HQ_HYbbVrtjCTJ25KzJHhjay-0i5tQ@mail.gmail.com>
Date: Tue, 14 Jan 2025 12:16:27 -0600
From: Rob Herring <robh@...nel.org>
To: Marc Zyngier <maz@...nel.org>
Cc: James Clark <james.clark@...aro.org>, Mark Brown <broonie@...nel.org>, kvmarm@...ts.linux.dev, 
	oliver.upton@...ux.dev, suzuki.poulose@....com, coresight@...ts.linaro.org, 
	James Clark <james.clark@....com>, Joey Gouly <joey.gouly@....com>, 
	Zenghui Yu <yuzenghui@...wei.com>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Mike Leach <mike.leach@...aro.org>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Mark Rutland <mark.rutland@....com>, 
	Anshuman Khandual <anshuman.khandual@....com>, Shiqi Liu <shiqiliu@...t.edu.cn>, 
	James Morse <james.morse@....com>, Fuad Tabba <tabba@...gle.com>, 
	Raghavendra Rao Ananta <rananta@...gle.com>, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 04/10] arm64/sysreg: Add a comment that the sysreg
 file should be sorted

On Mon, Jan 13, 2025 at 10:49 AM Marc Zyngier <maz@...nel.org> wrote:
>
> On Mon, 13 Jan 2025 15:43:39 +0000,
> James Clark <james.clark@...aro.org> wrote:
> >
> >
> >
> > On 12/01/2025 12:49 pm, Marc Zyngier wrote:
> > > On Tue, 07 Jan 2025 11:32:41 +0000,
> > > James Clark <james.clark@...aro.org> wrote:
> > >>
> > >> From: James Clark <james.clark@....com>
> > >>
> > >> There are a few entries particularly at the end of the file that aren't
> > >> in order. To avoid confusion, add a comment that might help new entries
> > >> to be added in the right place.
> > >>
> > >> Reviewed-by: Mark Brown <broonie@...nel.org>
> > >> Signed-off-by: James Clark <james.clark@....com>
> > >> Signed-off-by: James Clark <james.clark@...aro.org>
> > >> ---
> > >>   arch/arm64/tools/sysreg | 2 ++
> > >>   1 file changed, 2 insertions(+)
> > >>
> > >> diff --git a/arch/arm64/tools/sysreg b/arch/arm64/tools/sysreg
> > >> index b081b54d6d22..4ba167089e2a 100644
> > >> --- a/arch/arm64/tools/sysreg
> > >> +++ b/arch/arm64/tools/sysreg
> > >> @@ -48,6 +48,8 @@
> > >>   # feature that introduces them (eg, FEAT_LS64_ACCDATA introduces enumeration
> > >>   # item ACCDATA) though it may be more taseful to do something else.
> > >>   +# Please try to keep entries in this file sorted by sysreg
> > >> encoding.
> > >> +
> > >>   Sysreg   OSDTRRX_EL1     2       0       0       0       2
> > >>   Res0     63:32
> > >>   Field    31:0    DTRRX
> > >
> > > "Do as I say, don't do as I do".
> > >
> > > I don't think this makes any sense if we don't actually sort the file
> > > the first place.
> > >
> > >     M.
> > >
> >
> > I think it's ok if it avoids review comments that new entries should
> > be sorted. Or maybe we do the opposite and the comment should say this
> > file is allowed to be unsorted...
>
> The better option would be to add the comment *and* sort the file.
> Leading by example has some value, it seems.

IME, it's better if documentation just states what the tools enforce.

Can't we add something like this to the header generation:

$ grep '^Sysreg\s' arch/arm64/tools/sysreg | sort -n -k3 -k4 -k5 -k6 -k7 -c
sort: -:22: disorder: Sysreg ID_MMFR4_EL1       3       0       0
 2       6

Rob